This invention relates to a stack squaring device, particularly for a stack consisting of a plurality of thin sheets. The stack squaring device includes a horizontal conveyor to transport the stack from a reception area, via a squaring area into a discharge area. A stack stop is disposed in the discharge area and can be swung into the stack conveyance area. Two contact plates are disposed at the sides of the stack when it is in the squaring area and at least one of the contact plates is in the form of a vibrator plate. The vibrator plate is driven by a vibrator drive unit.
Such a stack squaring device for squaring a stack, consisting of a plurality of paper sheets or similar objects, is disclosed in German Published Application 3,712,104. This stack squaring device is connected to a horizontal conveyor system which comprises a plurality of individual longitudinal conveyors and which are placed at a distance to one another. A stack grid is disposed underneath the level at which the stacks are conveyed on the horizontal conveyor system. The stack grid comprises longitudinal bars which are orientated in parallel with the individual longitudinal conveyors. The stack squaring device further comprises a front stack stop which is perpendicular to and can also be displaced above the stack conveying level. The front end of the stack grid can be pivoted about a horizontal transverse axis and the stack grid is mounted in the horizontal conveyor system and can be lifted up over the stack conveying level with the help of a piston aggregate which engages with its back end with the stack bearing area which is formed by the longitudinal bars. Two vibrator plates and a press plate are arranged underneath and one press plate is arranged above the stack grid.
The prior art device has the drawback, that it is of a very complicated and costly construction. A stack can only be squared in an inclined position. Every stack which is to be squared must therefore be pivoted back and forth by the apparatus. Due to these steps, which are necessary due to the construction, the device is prone to breakdowns, particularly if operated continually. Furthermore, the extreme length of the squaring process and the costs that this incurs act detrimentally with regard to the rentability of the prior art device. The device can also only be fed and emptied by the horizontal conveyor, so that the device is very inflexible and is not suitable for other conveyor systems of a different construction.
In addition the squared stack loses its compacted state and its squareness during further transportation on the horizontal conveyor system.